The Ericksen-Leslie equations, describing the dynamic behavior of nematic liquid crystals, have been applied to a twisted nematic layer and have been numerically solved for a number of cases. The results account well for the observed dynamic behavior of displays using a twisted nematic layer. In particular, an explanation is given for the ’’bounce’’ in the optical transmission of a twisted nematic cell between polarizers after switching off the applied field. Materials having a frequency dependence of the sign of the dielectric anisotropy show a reversal of twist after the frequency of the applied field has been switched. This can also be explained. It is shown that fluid motion is essential to the occurrence of these phenomena.

The coloration and bleaching behavior of undoped bromide sodalite prepared by solid-state reaction and by various low-temperature hydrothermal reactions is studied. A high coloration sensitivity is obtained; for instance, a charge density of 0.5 μC/cm2 at 10 kV yields a contrast ratio of 2:1. The coloration and optical bleaching behavior is strongly dependent on the preparation method. A relation between bleaching rate and bromide deficit is found. A relation is suggested between residual coloration and the presence of oxygen on bromine sites. The effect of the doping with transition-metal ions on the bleaching behavior is studied. The doping with Fe, Ni, and Cu causes a considerable increase in bleaching rate.

Sodalites were prepared by both solid‐state and low‐temperature (80°C) hydrothermal reactions. Induction of cathodo‐chromism was studied and optimized. Undoped halide sodalites can be activated by firing in an oxidizing atmosphere. The coloration and optical bleaching sensitivities depend strongly on both the method of preparation and the activation treatment. The factors which determine the cathodochromic properties, e.g. bromine content, Al/Si ratio, and oxygen content, are discussed.

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